WASHINGTON (AP) — If the government "shuts down" next Tuesday, your mail will still come. Doctors will see Medicare patients. NASA will keep talking to the astronauts circling Earth on the Space Station. In fact, the majority of government will remain on the job.

The closings would hit random Americans first: vacationers hoping to take in Mount Rushmore or a Smithsonian museum. Homebuyers seeking government-backed mortgages. Veterans appealing the denial of disability benefits. Perhaps on the bright side — for some — tax audits would be suspended.

Troubles would spread the longer a shutdown lasted.

A prolonged furlough of more than one-third of civilian federal workers could mean delays in processing applications for new Social Security disability claims. Lost profits for businesses that sell goods or services to the government. Problems hotels and restaurants that rely on tourism near national parks. Longer waits for kids seeking delinquent child support.

And, of course, a shutdown would mean no paychecks for an estimated 800,000 furloughed workers. They might get paid later for the missed days but couldn't count on that. Don't blame them for slacking off; the law forbids volunteering to work for free from home.

Kaitlin Thomas, who toured the National Museum of American History on Friday, found the whole thing a little annoying.

"If the public is paying for this, why are they shutting it down?" said Thomas, visiting from New York City.

The deadline nearing, a government of more than 2.1 million civilian employees scrambled on Friday to update its plans determining who would stay and who would go home, what would get done and what would have to wait. The equation was complicated by the complexity of federal budget rules; some pots of money would be caught up in a shutdown and some wouldn't.

Ironically, a shutdown would have virtually no impact on President Barack Obama's health care law — the program at the heart of his showdown with House Republicans. The program that detractors dubbed "Obamacare" is set to roll out its individual insurance plans on Tuesday, government shutdown or no, and people hoping to sign up on that first day shouldn't be affected.

Some of the nation's behind-the-scenes health and safety work would stop, however. The Centers for Disease Control and Prevention would be severely limited in spotting or investigating disease outbreaks, from flu to that mysterious MERS virus from the Middle East. The government wouldn't process auto recall information or conduct new car safety testing.

A shutdown America could still go to war, Pentagon Comptroller Robert Hale told reporters Friday. But soldiers' pay might be delayed if closings lasted more than a week or so.

Other work that continues no matter how the political spat goes:

— Prison guards, FBI agents and the Border Patrol will be at their posts.

__The National Weather Service will make forecasts and issue storm warnings.

—NASA will man Mission Control in Houston to support the International Space Station and the two Americans among six people living aboard. But aside from that, only about 3 percent of NASA's 18,000 workers will be on the job.

—The White House will stay open. It's exempted from the federal law that requires many government employees to stop working if congressionally approved funding for their jobs expires. Obama could still take his scheduled trip to Asia the week of Oct. 6, if he chose to.

—The post office will keep delivering; its budget isn't affected because it comes from selling stamps and delivering packages.

— Workers in programs funded by user fees — such as immigration service employees who process green card applications and people who oversee truck and bus safety — also will stay on the job.

Federal courts have enough money to operate normally for about two weeks. But if a shutdown continued past mid-October, furloughs would begin. The Supreme Court says it's covered at least through next week.

One reason a shutdown would balloon over time concerns the legion of private contractors who carry out many of the government's functions. Some are paid through huge long-term contracts that wouldn't be affected anytime soon or their money comes from protected streams. Others would see their payments cut off but would keep their employees working for as long as they could, expecting the government to pay its tab eventually. But as cash ran low they might have to turn to layoffs.

For tourists and nature lovers, the effects would hit fast. A shutdown would quickly close all national parks, from Acadia to Yosemite, and national monuments and wildlife refuges. The Interior Department says campers would get 48 hours to pack up and leave.

And the IRS wants you to know: A shutdown is no reprieve for taxpayers. People who got a six-month filing extension are still up against an Oct. 15 deadline, even if some services their money is paying for have ground to a halt.